Synthetic food and cosmetic colorants are steadily being replaced by natural ones because of consumer preferences. Anthocyanins (polyphenolic pigments) are natural, water-soluble nontoxic pigments derived from fruits and vegetables, displaying a variety of colors from orange to blue. Because of their antioxidant properties, they may also have beneficial influence on human health (Shenoy, 1993, Curr. Sci. 64: 575-579). A drawback in the use of anthocyanins as food or cosmetic colorants is the presence of unpleasant taste and/or odor, particularly in anthocyanins extracted from red cabbage.
Anthocyanins are produced by chopping or crushing the fruit or vegetable and subsequent infusion of water acidified with a common food acid. This extract is then concentrated by non-chemical separation techniques. Pigment extracts from plant sources generally contain mixtures of different anthocyanin molecules, which vary by their level of hydroxylation, methylation and acylation. In some instances, such as anthocyanins extracted from red cabbage and radish, the extracts also contain undesirable components that contribute to unpleasant taste or odor of the extract. These factors can vary in the source plant from year to year, and are influenced by weather and environmental factors. Another challenge for the commercial production of anthocyanin pigments from plants is that harvest is often limited to once a year. This means a large volume of extract has to be prepared and stored for an extended period of time to supply the needs of the food industry throughout the year. Special storage conditions often have to be available due to the instability of anthocyanins. Additionally, the unpleasant taste and odor often develop after purification of the anthocyanin or other natural plant products from whole plants or plant tissues.